01The verdict: is Grand Coulee water safe?
Grand Coulee's drinking water has significant quality concerns based on EPA testing data. With a grade of A- (89.2/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 2 water systems serve approximately 1,544 residents using groundwater (wells).
3 unresolved violations on record
EPA records show open compliance items for this system. Most are administrative, but unresolved items are worth watching.
See what was cited ↓Lead is well under the limit
90th-percentile lead is 0.0 ppb — beneath the 15 ppb federal action level and under the 5 ppb watch threshold.
See the trend ↓Check back after the next refresh
EPA data updates on a rolling basis; we fold in new samples and violations every month.
Get alerts ↓Grand Coulee's drinking water received a grade of A- (89.2 out of 100), indicating good water quality. The city's 2 water systems serve approximately 1,544 residents using purchased ground water.
Lead levels were measured at 0.0 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program. The system has 6 violations on record, including 1 health-based violation. 3 remain unresolved.
Grand Coulee ranks #51 out of 294 cities in Washington for water quality, placing it above average in the state. Grand Coulee purchases its water from a regional wholesaler, meaning quality depends on both the supplier's treatment and the local distribution system's condition. As a small community water system, Grand Coulee may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
02What's in Grand Coulee's water
Every contaminant flagged in Grand Coulee, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 0.0 | 15 | ppb | Inorganic | Safe |
Cities ranked by 90th-percentile lead PF PFAS in Washington
Cities ranked by compounds detected Cu Copper in Washington
Cities ranked by 90th-percentile copper
03Grand Coulee's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. The system has 6 violations on record, including 1 health-based violation. 3 remain unresolved.
All ten of the last ten years were clean — no EPA violations recorded for Grand Coulee.
▼ Down 10 ppb since 1993. Latest reading: 0 ppb (2025) — 0% of the action level. Sampled at higher-risk homes (90th percentile).
04Where Grand Coulee's water comes from
Grand Coulee purchases its water supply from a regional wholesale provider rather than treating raw water directly.
Purchased Groundwater
Water is bought from a regional wholesaler; quality starts at the supplier's intake and treatment.
Wholesale supplier
Primary treatment happens at the wholesaler; the local utility maintains disinfectant residual in its pipes.
2 systems
2 water systems (1 wholesaler), operated under local government ownership.
1,544 people
Residents served across Grand Coulee's service area.
Water quality depends on both the wholesaler's treatment standards and the condition of Grand Coulee's local distribution pipes and storage facilities. Purchased water systems are common in suburban areas and smaller communities that lack the infrastructure for independent treatment. The system is operated by local government ownership and serves approximately 1,544 people through 2 water systems.
| System name | PWSID | Population | Source |
|---|---|---|---|
| GRAND COULEE WATER DEPT CITY OF | WA5328700 | 1,428 | Purchased Groundwater |
| NORTH SHORE ACRES | WA5303370 | 116 | Groundwater |
Water bodies near Grand Coulee
These water bodies shape the regional watershed and can indirectly affect groundwater quality.
05Pressure on Grand Coulee's watershed
Outside forces that shape what reaches the treatment plant. None of these is a verdict on the tap by itself — but each adds pressure worth knowing about.
Flood & storm history
2 federal disaster declarations on record for Grant County. Flooding and severe storms can overwhelm treatment plants, cause sewage overflows, and push runoff into supplies.
Drought
Grant County is in D1 (moderate drought) per the U.S. Drought Monitor (week of Jul 2026). Drought can raise disinfection-byproduct levels and taste/odor issues as utilities draw from lower reservoirs.
06How Grand Coulee compares
Scores for nearby Washington cities on one line, with the average marked.
dashed line = Washington average (53/100)
Grand Coulee scores 89.2/100 — above the Washington average of 53/100. It outscores 9 of 10 nearby cities. Full Washington rankings →
42.3 / 100FTacoma, WA
32.2 / 100FVancouver, WA
32.9 / 100FSpokane, WA
39.2 / 100FKent, WA
44.4 / 100ABellevue, WA
91.6 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
07What to do at home
Steps matched to what testing actually found in Grand Coulee's water — not generic advice.
A basic carbon filter still helps
Grand Coulee's water meets federal standards, but a simple carbon filter improves taste and adds a margin of safety against short-term issues.
Compare tested filters →Read your utility's annual report
Every utility must publish a yearly Consumer Confidence Report with its own testing results. It pairs well with the independent data on this page.
How to read a CCR →Watch for Grand Coulee alerts
We refresh EPA data monthly and surface new violations, advisories, and boil-water notices for your county on this page.
All water alerts →Frequently asked questions
Is Grand Coulee, WA tap water safe to drink?
Grand Coulee's water quality earned a grade of A- (89.2/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #51 out of 294 cities tested in Washington.
What contaminants are in Grand Coulee's water?
Lead was measured at 0.0 ppb (90th percentile). 6 violations are on record.
How is Grand Coulee's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Grand Coulee?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Grand Coulee's water come from?
Grand Coulee's water is sourced from Purchased ground water. The city has 2 water systems serving approximately 1,544 residents.
What health violations has Grand Coulee's water system had?
Grand Coulee has 1 health-based violation on record. The most recent violation was recorded in July 2010. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 3 violations remain unresolved.
Is Grand Coulee's groundwater at risk of contamination?
Grand Coulee uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 6 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Grand Coulee's water compare to other cities?
Grand Coulee ranks #51 out of 294 cities in Washington (better than 83% of state cities) and #2960 out of 15382 cities nationally (81th percentile). The grade of A- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.